tree 75ebbfaed4a5b3811e73db6d548cb61b6a22e99c
parent d6c617782ab73c5552f4bfea9e0cede8431d1a65
author Zhizhou Yang <zhizhouy@google.com> 1536191417 -0700
committer chrome-bot <chrome-bot@chromium.org> 1536611625 -0700

Bisect tool: Pass/Transformation level bisection for bad item

This patch provides pass and transformation level bisection support for
existing bisection tool.

Usage: When `--pass_bisect=script_path` is set, pass/transformation
level bisection will be turned on. It only works when prune is set to
False. Orignial bisection will end with the first bad item it find. This
patch then will rebuild and bisect the bad item using bad compiler with
pass/transformation level bisect limit. It will end up with the bad pass
name/index and bad transformation index for that pass.

Notice that this patch still need support from LLVM with this review:
https://reviews.llvm.org/D50031, which allows debugcounter to print info
we need.

The patch eventally add a new binary search process, and two build
function to saparately build with pass and transformation level limit.
A new BinarySearcherForPass is also introduced for pass level bisect.

The workflow is:
    1) get bad item and command to build it with existing bisection.
    2) rebuild bad item with pass level limit to -1 to get total pass
       count.
    3) binary search pass index until we got bad pass.
    4) rebuild bad item with pass limit we get and also set
       transformation level limit to -1 to get total number of
       transforamtion.
    5) binary search transformation index until we got bad
       transformation.

BUG=chromium:878954
TEST=Ran test successfully with Android compiler wrapper. Will add
unittests once new patch in LLVM applied.

Change-Id: I08f376f15d12eea232da5887981c44184ffb9568
Reviewed-on: https://chromium-review.googlesource.com/1208855
Commit-Ready: Zhizhou Yang <zhizhouy@google.com>
Tested-by: Zhizhou Yang <zhizhouy@google.com>
Reviewed-by: Caroline Tice <cmtice@chromium.org>